This study describes teachers' experiences of success and failure in teaching through interviews. The analytical framework for this study was based on Activity Theory (Leon'tev, 1978), and the research methods were developed by Herzberg et al. (1959). The inclusion of factors identified by Seligman (2006) and Maslach (1982) allowed for additional analyses. The central finding of this study was that the motivation to teach is derived from the caring relationship of the teacher and the student. This motivation is based on meaning rather than satisfaction of personal needs. Participants described success and failure in teaching mostly with regard to student growth. Student growth was measured in terms of improved affective or cognitive performance and measured anecdotally more frequently than by assessment data. The evaluation of success or failure was mostly by self-reflection of the teacher rather than through supervisorial feedback, and indicator systems were self-monitored, without direct supervisorial dialogue. Failure situations generally did not have negative performance effects, but failure led to negative mental health and interpersonal relations effects. Mental health and interpersonal relations were highly correlated factors for teachers, and areas of focus in efforts to prevent teacher burnout. Moreover, success was frequently achieved through overcoming failure situations, and success led to an increased interest in the work itself and improved performance [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]